Photographically sensitive X-ray film elements



April 4, 1950 o. w. MURRAY 2,502,529

PHOTOGRAPHICALLY SENSITIVE X-RAY FILM ELEMENTS Filed Sept. 18, 1946 FIG.1.

FLUORESCENT LEAD AND BARIUM SULFATE AND SODIUM-0'SULFOBENZALDEHYDE POLYVINYL ACETAL GELATINO SILVER HALIDE EMULSION GELATlN-PHENOL SUBLAYER CELLULOSE ACETATE BASE FLUORESCENT LEAD AND BARIUM SULFATE AND GELATIN- CELLULOSE ACETATE-PHTHALATE-SODIUMSALT GELATINO SILVER HALIDE EMULSION GELATIN-PHENOL SUBLAYER CELLULOSE ACETATE BASE FLUORESCENT LEAD AND BARIUM SULFATE AND SODIUM CASElNATE-GELATIN GELATINO SILVER HALIDE EMULSION GELATlN-PHENOL SUB'LAYER GELLULOSE ACETATE BASE WMIIIIIM'IIA INVENTOR.

Ofi's Willard Murray BY A T TORNE Y Patented Apr. 4, 1950 UNITED I STATES PHOTOGRAPHICALIJY SENSITIVE X-RA FILM ELEMENTS Otis Willard Murray, Fords, N. J., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application September 18, 1946, Serial No. 697,829

3 Claims.

This invention relates to photographic elements which have a light-sensitive layer and a coactive, removable, fluorescent layer. More particularly it relates to X-ray film elements which have a light-sensitive silver halide emulsion layer and a contiguous, removable, fluorescent layer. An object of this invention is to provide improved radiographic elements. A further object is to provide X-ray films and papers with removable coatings. A related object is to provide such elements with removable coatings which do not come off in a developer solution. A still further object is to provide such elements with fluorescent coatings which are readily removable in water. Still other objects will be apparent from the following description.

The above objects are attained and commercially practical radiation-sensitive elements provided by coating the hydrophilic colloid silver I halide emulsions of photographic elements with a solution of a water-soluble, aqueous-alkalinedeveloper-insoluble colloid in a water-soluble, volatile solvent having no solvent action on the colloid binding agent of the emulsion and especially a volatile alcohol, for example, methanol or ethanol containing less than of water, said solutions having a fluorescent pigment which is activated by X-rays. The solvent is allowed .to evaporate. Other useful solventsinclude dioxane and acetone and mixtures ,contain'- ing not more than 10% of water.

The use of such solvents or mixtures has the advantage that it does not adversely affect the fluorescent properties of the fluorescent pigment nor-embed the pigment in the emulsion layers. When solutions of the colloids in water alone are used with aqueous dispersions of fluorescent pig-. ments, the hydrophilic colloids of the emulsion layer swell under the influence of the overcoating and the pigments become embedded in the silver halide emulsion layers. The resulting emulsion layers are permanently endowed with an undesirable haze which complicates the reading of the finished radiographs The fluorescent pigment layers formed in accordance with the present invention are completely removed and no pigment haze is left in the emulsion layer.

A satisfactory X-ray fihn element can be made by coating a transparent film base with a colloid, e. g., gelatino-silver halide emulsion, and allowing it to dry. One of the silver halide emulsion coatings is then coated with a dispersion of a fluorescent pigment in a methanol orethanol solution of a water-Soluble, aqueous-alkalinedeveloper-insoluble colloid and allowed to dry. The element is exposed by means of X-rays and developed in any conventional X-ray film developing bath. The element is then washed in wa ter which removes the coating of fluorescentpigment. It is then fixed and again washed with water and finally dried. The resulting radiograph is free from haze due to pigment particles and has a clear surface. In addition, the developer solution is free from contamination with the colloid and fluorescent pigment. The washing step after development can be eliminated if desired. X-ray films which have a hydrophilic colloid silver halide emulsion layer on each surface need only have one of the emulsion layers coated with the novel fluorescent layers hereof. Both surfaces may be coated in order to increase the strength of the fluorescent radiation, however.

In the preferred aspect of the invention, there is used as the water-soluble, aqueous-alkalinedeveloper -insoluble colloid, the water-soluble polyvinyl acetals of aromatic monoaldehydes having sulfonic acid or carboxylic acid groups and alkali metal salts thereof. Suitable acetals of this type can be prepared from polyvinyl alcohols and substantially completely hydrolyzed polyvinyl esters and aldehyde carboxylic or sulfonic acids, such as ortho-, meta-, and parabenzaldehyde sulfonic acid, acetaldehyde disulfonic acid, naphthaldehyde sulfonic acids, e. g., 1-naphthaldehyde-2-sulfonic acid, l-naphthaldehydel-sulfonic acid, 2-naphthaldehyde-5-sulfonic acid, and the corresponding carboxylic acids, by condensation in the presence of mineral acids or acid salts after the manner described in German Patent 643,650. Such acetals are insoluble in aqueous alkaline photographic developer solutions containing 2% or more by weight of dissolved inorganic salts. The condensation should be carried out until the vinyl. alcohol groups have been acetalized.

The invention will be further illustrated by the following examples and in the drawin wherein: I

Fig. 1 is a cross-section of the film of Example I.

Fig. 2 is a cross-section of the film of Exam ple II. v

Fig. 3 is a cross-section of the film of Exam ple III. Fig. 4 is a cross-section of the film of Exam ple IV.

Example I Asshown in Fig. 1 of the drawing cellulose acetate film base I is provided with a thin gelatin phenol sublayer 2 over which is coated a gelatinosilver bromide emulsion of an X-ray type at a temperature of about F. to a weight of about mg. of silver bromide per square decimeter of surface and dried whereby layer 3 is formed; A dispersion of the following composition is prepared by admixing the components with stirring:

Sodium-o-sulfobenzaldehyde polyvinyl ace- The fluorescent mixed crystals of lead and barium sulfate contain 80% of the latter and 20% of the former and are obtainable as disclosed in United States Patent 2,289,997. The resulting solution is coated on the gelatino-silver halide emulsion layer to a Weight of 60 mg. per square decimeter forming layer 4. The element is dried. All operations are carried out in the absence of actinic radiations. The resulting element is given an unscreened exposure by means of X-rays and developed in a bath of the composition:

N-methyl-p-aminophenol sulfate grams 2.5 Sodium sulfite (anhydrous) do 75.0 Hydroquinone do 3.0 Borax do 5.0 Water liter 1.0

The developed element is washed thoroughly in water whereby the fluorescent coating is removed. The developed and washed element is then fixed ina solution of the composition:

Sodium thiosulfate grams 240 Sodium sulfite do 6 Boric acid do 6 Potassium alum do 12 Acetic acid (28%) ..cc 35 Water to liter 1 The finished radiograph, after washing, is free from surface stain and haze, being substantially free from any fluorescent leador barium sulfates.

Example II A similar element is made by substituting ,for the polyvinyl acetal of Example I, five grams of sodium alginate and is shown in Fig. 2 of the drawing. The water was increased to 150 cc. and the ethanol reduced to 150 cc. The fluorescent coating was readily removed by washing after exposure and development after the manner set forth in Example I.

Example III A similar element shown in Fig. 3 of the drawing is made by substituting for the polyvinyl acetal of Example I, 15 grams of cellulose acetateacid phthalate sodium salt and one gram of gelatin resulting in layer 6. The water-alcohol ratio was changed to a 60-40 mixture. It gives similar results upon exposure-and processing as described in Example I.

Example IV A similar element, shown in Fig. 4 of the drawing is made by substituting for the polyvinyl acetal of Example I, 2.0 grams of a mixture of 20 The colloid silver halide emulsion layers may contain in addition to the light-sensitive silver halide, e. g., silver chlorides, silver-chloride-broinide, silver-iodobromide, etc., various sensitizing dyes and other materials which are common in emulsion layers. Such additional materials include fog inhibiting agents, emulsion hardeners, emulsion preservatives, etc.

In place of the specific fluorescent pigments of the above examples, there can be substituted other such materials which exhibit fluoresence under the influence of X-rays. Suitable additional agents include calcium tungstate, fired lead sulfate, and fired barium sulfate, as described in United States Patents 2,289,384 and. 2,336,815, and zinc sulfide. These materials emit under such rays light in the ultra-violet and blue regions of the spectrum. Agents which prevent after-glow can be added if desired so that the intensification will not be prolonged after X-ray exposure has ceased.

The radiation-sensitive layers can be deposited on various supports, e. g., paper, transparentized paper, cellulose derivatives, e. g., cellulose acetate, cellulose nitrate, superpolymers, e. g., styrene, methyl methacrylate, nylon, glass, etc.

The fluorescent coatings have the advantage that they form satisfactory anti-abrasion layers. Their advantage is that they are simple, economical, and do not contaminate the developer. The major advantage is that these layers eliminate the need for screens and yield films which are easily handled in industrial work.

As many widely different embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is .not to be limited except as defined by the claims.

What is claimed is:

1. An X-ray film element comprising a transparent film support, a hydrophilic colloid-silver halide emulsion layer on the support and a contiguous fluorescent coating comprising a pigment which exhibits fluoresence when irradiated by X-rays dispersed in a water-soluble, aqueousalkaline-developer-insoluble polyvinyl acetal of an aromatic aldehyde containing a solubilizing group taken from the class consisting of free carboxylic acid and free sulfonic acid groups and their water-soluble salts.

2. An X-ray film element comprising a transparent film support, a hydrophilic colloid-silver halide emulsion layer on the support and a contiguous fluorescent coating comprising a pigment which exhibits fluorescence when irradiated by X-rays dispersed in a water-soluble, aqueous-alkaline-developer-insoluble polyvinyl acetal of an aromatic aldehyde containing an alkali metal sulfonate group.

'3. An X-ray film element comprising a transparent film support, a hydrophilic colloid-silver halide emulsion layer on the support and a contiguous fluorescent coating comprising a pigment which exhibits fluoresence when irradiated by X rays dispersed in a Water-soluble, aqueous-alkaline-developer-insoluble sodium-o-sulfobenzaldehyde acetal of polyvinyl alcohol.

OTIS WILLARD MURRAY.

REFEEENCES CITED The following references are of record in. th file of this patent:

UNITED STATES PATENTS Number Name Date 1,954,337 Staud Apr. 10, 1934 2,245,218 Murray et al June 10, 1941 2,303,917 Dietz Dec. 1, 19.42 2,319,080 Nadeau et al. May 11,1943 2,319,102 Albers et al. May 11,1943 

1. AN X-RAY FILM ELEMENT COMPRISING A TRANSPARENT FILM SUPPORT, A HYDROPHILIC COLLOID-SILVER HALIDE EMULSION LAYER ON THE SUPPORT AND A CONTIGUOUS FLUORESCENT COATING COMPRISING A PIGMENT WHICH EXHIBITS FLUORESENCE WHEN IRRADIATED BY X-RAYS DISPERSED IN A WATER-SOLUBLE, AQUEOUSALKALINE-DEVELOPER-INSOLUBLE POLYVINYL ACETAL OF AN AROMATIC ALDEHYDE CONTAINING A SOLUBILIZING 